Halloween is growing closer, and to celebrate we're turning our gaze to the dark side of life hacking. Welcome to Lifehacker's third Evil Week.

The whole idea of "evil" is a bit tongue-in-cheek, but one common theme unites most of the topics we're covering: Knowledge is power, and whether you use that power for good or evil is in your hands. Learning to crack passwords teaches you security practices. A better understanding of lying and manipulation earns you the ability to detect them. This week we'll cover a breadth of topics from the dark side and share some of our favorite evil posts from the past. There's a time and a place for bad behavior, and that's right here and now. Join us as we welcome Evil Week once more.